DENJIRO: Today, we’re taking a look at this rock. It’s called “the Vikings’ sunstone.”
BOY: What’s a sunstone?
DENJIRO: The name of the mineral is “calcite.” It’s not a rare rock by any means. It’s said that Vikings used the sunstone when sailing to check the position of the sun after it had set. So how can you tell the position of the sun with this rock?
I’ve recreated the sky during the day using light and a fish tank. Let’s use this polarizing filter to take a look at the fish tank, or the sky.
BOY: It got darker!
DENJIRO: Light vibrates in various directions. The sky you see from over here has lots of light that is vibrating vertically. This filter lets through a lot of light that is vibrating in the direction of the arrow. So when the arrow is pointing up, it’s bright, and when it’s horizontal, it’s dark.
NARRATOR: By using this property, you can locate the sun when you can’t see it.
DENJIRO: I have a vertical filter and a horizontal filter put next to each other. I’m going to look for the angle where they both have the same brightness. When I find the right angle, I’m going to place an arrow pointing at the sun. Now, even if I can’t see the sun, I can tell where the sun is by finding the angle where the two filters have the same brightness.
Calcite has the same property as a polarizing filter. I’m going to attach a piece of paper with a hole cut into it to make a window. When I look through the calcite from the other side, you can see that there are two windows. They play the same role as the two filters I used earlier. Look for the angle where the two filters have the same brightness, and mark which direction where the sun is. Now, you can always use the arrow to find the sun by seeing where the two windows appear the same. Vikings often sailed in high-latitude locations where the sun is often hiding behind the horizon. It is thought that they used calcite to find the location of the hidden sun to sail.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!”
20 окт 2022
